var _api,//对外API
    _keyMap = {//特殊键
        backspace: 8, tab: 9, clear: 12,
        enter: 13, 'return': 13,
        esc: 27, escape: 27, space: 32,
        left: 37, up: 38, right: 39, down: 40,
        del: 46, 'delete': 46,
        home: 36, end: 35,
        pageup: 33, pagedown: 34,
        ',': 188, '.': 190, '/': 191,
        '`': 192, '-': 189, '=': 187,
        ';': 186, '\'': 222,
        '[': 219, ']': 221, '\\': 220
    },
    _scope = 'all',//默认热键范围
    _modifier = {//修饰键
        '⇧': 16, shift: 16,
        '⌥': 18, alt: 18, option: 18,
        '⌃': 17, ctrl: 17, control: 17,
        '⌘': 91, command: 91
    },
    _downKeys = [],//记录摁下的绑定键
    modifierMap = {
        16: 'shiftKey',
        18: 'altKey',
        17: 'ctrlKey',
        91: 'metaKey'
    },
    _mods = { 16: false, 18: false, 17: false, 91: false },
    //返回键码
    code = function (x) {
        console.log();
        return _keyMap[x] || x.toUpperCase().charCodeAt(0);
    },
    _handlers = {};
// F1~F12 特殊键
for (var k = 1; k < 20; k++) {
    _keyMap['f' + k] = 111 + k;
}

//设置获取当前范围（默认为'所有'）
function setScope(scope) { _scope = scope || 'all'; }
function getScope() { return _scope || 'all'; }
//绑定事件
function addEvent(object, event, method) {
    if (object.addEventListener) {
        object.addEventListener(event, method, false);
    } else if (object.attachEvent) {
        object.attachEvent('on' + event, function () { method(window.event); });
    }
}
//判断摁下的键是否为某个键，返回true或者false
function isPressed(keyCode) {
    if (typeof (keyCode) === 'string') {
        keyCode = code(keyCode);//转换成键码
    }
    return _downKeys.indexOf(keyCode) !== -1;
}
//获取摁下绑定键的键值
function getPressedKeyCodes(argument) { return _downKeys.slice(0); }
//处理keydown事件
function dispatch(event) {
    var key = event.keyCode, scope, asterisk = _handlers['*'];

    //搜集绑定的键
    if (_downKeys.indexOf(key) === -1) _downKeys.push(key);
    //Gecko(Friefox)的command键值224，在Webkit(Chrome)中保持一致
    //Webkit左右command键值不一样
    if (key === 93 || key === 224) key = 91;
    if (key in _mods) {
        _mods[key] = true;
        // 将特殊字符的key注册到 hotkeys 上
        for (var k in _modifier) if (_modifier[k] === key) hotkeys[k] = true;
        if (!asterisk) return;
    }
    //将modifierMap里面的修饰键绑定到event中
    for (var e in _mods) _mods[e] = event[modifierMap[e]];

    //表单控件控件过滤 默认表单控件不触发快捷键
    if (!hotkeys.filter.call(this, event)) return;
    //获取范围 默认为all
    scope = getScope();

    //对任何按键做处理
    if (asterisk) for (var i = 0; i < asterisk.length; i++) {
        if (asterisk[i].scope === scope) eventHandler(event, asterisk[i], scope);
    }

    // key 不在_handlers中返回
    if (!(key in _handlers)) return;

    for (i = 0; i < _handlers[key].length; i++) {
        //找到处理内容
        eventHandler(event, _handlers[key][i], scope);
    }
}

function eventHandler(event, handler, scope) {
    var modifiersMatch;
    //看它是否在当前范围
    if (handler.scope === scope || handler.scope === 'all') {
        //检查是否匹配修饰符（如果有返回true）
        modifiersMatch = handler.mods.length > 0;
        for (var y in _mods) {
            if ((!_mods[y] && handler.mods.indexOf(+y) > -1) ||
                (_mods[y] && handler.mods.indexOf(+y) === -1)) modifiersMatch = false;
        }
        // 调用处理程序，如果是修饰键不做处理
        if ((handler.mods.length === 0 && !_mods[16] && !_mods[18] && !_mods[17] && !_mods[91]) || modifiersMatch || handler.shortcut === '*') {
            if (handler.method(event, handler) === false) {
                if (event.preventDefault) event.preventDefault();
                else event.returnValue = false;
                if (event.stopPropagation) event.stopPropagation();
                if (event.cancelBubble) event.cancelBubble = true;
            }
        }
    }
}

//解除绑定某个范围的快捷键
function unbind(key, scope) {
    var multipleKeys = getKeys(key), keys, mods = [], obj;
    for (var i = 0; i < multipleKeys.length; i++) {

        //将组合快捷键拆分为数组
        keys = multipleKeys[i].split('+');

        //记录每个组合键中的修饰键的键码 返回数组
        if (keys.length > 1) mods = getMods(keys);

        //获取除修饰键外的键值key
        key = keys[keys.length - 1];
        key = code(key);

        //判断是否传入范围，没有就获取范围
        if (scope === undefined) scope = getScope();

        //如何key不在 _handlers 中返回不做处理
        if (!_handlers[key]) return;

        //清空 handlers 中数据，
        //让触发快捷键键之后没有事件执行到达解除快捷键绑定的目的
        for (var r = 0; r < _handlers[key].length; r++) {
            obj = _handlers[key][r];
            //判断是否在范围内并且键值相同
            if (obj.scope === scope && compareArray(obj.mods, mods)) {
                _handlers[key][r] = {};
            }
        }
    }
}
//循环删除handlers中的所有 scope(范围)
function deleteScope(scope) {
    var key, handlers, i;
    for (key in _handlers) {
        handlers = _handlers[key];
        for (i = 0; i < handlers.length;) {
            if (handlers[i].scope === scope) handlers.splice(i, 1);
            else i++;
        }
    }
}
//比较修饰键的数组
function compareArray(a1, a2) {
    if (a1.length !== a2.length) return false;
    for (var i = 0; i < a1.length; i++) {
        if (a1[i] !== a2[i]) return false;
    }
    return true;
}
//表单控件控件判断 返回 Boolean
function filter(event) {
    var tagName = (event.target || event.srcElement).tagName;
    //忽略这些标签情况下快捷键无效
    return !(tagName === 'INPUT' || tagName === 'SELECT' || tagName === 'TEXTAREA');
}
//修饰键转换成对应的键码
function getMods(key) {
    var mods = key.slice(0, key.length - 1);
    for (var i = 0; i < mods.length; i++) mods[i] = _modifier[mods[i]];
    return mods;
}
//处理传的key字符串转换成数组
function getKeys(key) {
    var keys;
    key = key.replace(/\s/g, '');//匹配任何空白字符,包括空格、制表符、换页符等等
    keys = key.split(',');
    if ((keys[keys.length - 1]) === '') keys[keys.length - 2] += ',';
    return keys;
}

//在全局document上设置快捷键
addEvent(document, 'keydown', function (event) {
    dispatch(event);
});
addEvent(document, 'keyup', function (event) {
    clearModifier(event);
});
//清除修饰键
function clearModifier(event) {
    var key = event.keyCode,
        i = _downKeys.indexOf(key);

    if (i >= 0) _downKeys.splice(i, 1);

    //修饰键 shiftKey altKey ctrlKey (command||metaKey) 清除
    if (key === 93 || key === 224) key = 91;
    if (key in _mods) {
        _mods[key] = false;
        for (var k in _modifier) if (_modifier[k] === key) hotkeys[k] = false;
    }
}
//主体hotkeys函数
function hotkeys(key, scope, method) {
    var keys = getKeys(key), mods = [], i = 0;
    //对为设定范围的判断
    if (method === undefined) {
        method = scope;
        scope = 'all';
    }
    //对于每个快捷键处理
    for (; i < keys.length; i++) {
        key = keys[i].split('+');
        mods = [];
        //如果是组合快捷键取得组合快捷键
        if (key.length > 1) {
            mods = getMods(key);
            key = [key[key.length - 1]];
        }
        //转换成键码
        key = key[0];
        key = key === '*' ? '*' : code(key);
        //判断key是否在_handlers中，不在就赋一个空数组
        if (!(key in _handlers)) _handlers[key] = [];
        _handlers[key].push({ shortcut: keys[i], scope: scope, method: method, key: keys[i], mods: mods });
    }
}
_api = {
    setScope: setScope,
    getScope: getScope,
    deleteScope: deleteScope,
    getPressedKeyCodes: getPressedKeyCodes,
    isPressed: isPressed,
    filter: filter,
    unbind: unbind
};

for (var a in _api) hotkeys[a] = _api[a];
export default hotkeys